2145991 has 2 divisors, whose sum is σ = 2145992. Its totient is φ = 2145990.

The previous prime is 2145977. The next prime is 2146003. The reversal of 2145991 is 1995412.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 2145991 - 2¹¹ = 2143943 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2145191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1072995 + 1072996.

It is an arithmetic number, because the mean of its divisors is an integer number (1072996).

2^2145991 is an apocalyptic number.

2145991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2145991 is an equidigital number, since it uses as much as digits as its factorization.

2145991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 31.

The square root of 2145991 is about 1464.9201343418. The cubic root of 2145991 is about 128.9860169528.

It can be divided in two parts, 2145 and 991, that added together give a square (3136 = 56²).

The spelling of 2145991 in words is "two million, one hundred forty-five thousand, nine hundred ninety-one".